Colorectal cancer is becoming the leading cause of cancer deaths in people under 50, with rates rising 2.9% annually among younger adults. A groundbreaking blood test in development at City of Hope could transform how we catch the disease early, offering screening during routine annual exams for people as young as 18 years old.

Why Are Younger Adults Getting Colorectal Cancer More Often?

The numbers are striking. Colorectal cancer rates in adults under 50 have increased by 63% since 1988, jumping from 8 cases per 100,000 people to 13 per 100,000. The trend is particularly pronounced in rectal cancer, which is rising faster than colon cancer in younger populations. People born in 1990 are twice as likely as those born in 1950 to develop colon cancer, and four times as likely to develop rectal cancer.

Experts believe something fundamental changed in our environment or diet between 1950 and 1990 that continues to drive this increase. The culprits likely include:

• Western Diet Patterns: High animal fat, high carbohydrates, relatively lower vegetable intake, red and processed meat consumption, refined grains, and processed sugars have all been linked to increased colorectal cancer risk.
• Food Industry Changes: The rise of fast food across the country, increased use of preservatives, and widespread adoption of plastic food containers containing microplastics occurred during the same period colorectal cancer rates began climbing.
• Gut Microbiome Shifts: Changes in the bacteria living in our intestinal tract may be contributing to the increase, potentially driven by dietary habits and reduced exercise levels.

Interestingly, obesity and diabetes, traditionally considered major risk factors, don't fully explain the trend. Most younger people diagnosed with colorectal cancer are neither obese nor diabetic, suggesting other environmental or dietary factors are at play.

What Are the Warning Signs of Rectal Cancer in Younger People?

Rectal cancer symptoms in younger adults often go unrecognized or are misattributed to other conditions. The most common warning sign is rectal bleeding, which can appear as bright red to dark red blood in the stool or on toilet paper. This symptom is particularly common in younger patients with rectal cancer, but it's frequently confused with hemorrhoids or, in women, menstruation.

Other symptoms include abdominal pain, changes in bowel habits, constipation, thinner stools, fatigue, weight loss, and anemia. The challenge is that many younger patients face delayed diagnoses because symptoms are misattributed to other conditions. One gastroenterologist at City of Hope noted that nearly every young patient he has diagnosed with colon or rectal cancer was initially told they had hemorrhoids. As a result, three-fourths of younger patients are diagnosed with advanced disease.

"Any change in your gastrointestinal tract should not be ignored, and so any change in your GI function should be investigated by a doctor, and the most concerning signs that should prompt an investigation include any sign of blood in the stool," said Dr. Jatin Roper, a gastroenterologist with Duke Health.

Dr. Jatin Roper, Gastroenterologist at Duke Health

It's worth noting that some people with rectal cancer have no symptoms at all, making regular screening even more critical.

How Can a Blood Test Change Colorectal Cancer Screening?

City of Hope is developing a blood test designed to detect colorectal cancer early in adults under 50. The test, developed by Dr. Ajay Goel, could allow screening during annual exams for individuals as young as 18, a significant shift from current guidelines that recommend colonoscopy starting at age 45.

The potential impact is enormous. When colorectal cancer is detected at stage 1 or at the advanced polyp stage, it is nearly 100% curable. Currently, colonoscopy remains the standard screening method, but it requires scheduling, preparation, and recovery time. A simple blood test could remove these barriers, especially for younger adults who may not realize they're at risk.

"If you detect colorectal cancer early, at stage 1 or at the advanced polyp stage, it is nearly 100% curable. This test, when it becomes available, could be a game-changing public health breakthrough," said Dr. Ajay Goel, professor and chair of the department of molecular diagnostics and experimental therapeutics at City of Hope.

Dr. Ajay Goel, Professor and Chair of Molecular Diagnostics at City of Hope

Beyond the blood test, City of Hope is investigating how the microbiome, diet, and environmental factors influence cancer risk and treatment response. The organization is also conducting clinical trials to improve treatment outcomes for younger patients, including a Phase 2 study testing chemotherapy and immunotherapy combinations for early-stage rectal cancer to help preserve fertility and organ function.

Steps to Reduce Your Colorectal Cancer Risk

While there is no guaranteed way to prevent colorectal cancer, experts recommend several evidence-based actions:

• Schedule Screening Early: For people at average risk, colonoscopy or stool-based screening should begin at age 45. If your 45th birthday is approaching, plan one year in advance to schedule a screening with your doctor.
• Consider Stool-Based Tests: If you can't make time for a colonoscopy or lack transportation after the procedure, stool-based tests such as Cologuard and fecal immunochemical tests (FIT) are effective alternatives. A positive result on either test should be followed up with a colonoscopy.
• Monitor Your Diet: Reduce consumption of red and processed meat, refined grains, and processed sugars. Increase intake of vegetables and whole foods to support gut health and reduce cancer risk.
• Report Any GI Changes: Don't dismiss changes in bowel habits, blood in stool, abdominal pain, or unexplained weight loss. Seek medical evaluation promptly, as early detection is critical for younger adults.

The rising rates of colorectal cancer in younger adults underscore the importance of awareness and early screening. With new diagnostic tools like the blood test in development at City of Hope, the future of colorectal cancer detection may become simpler and more accessible, potentially catching the disease when treatment is most effective.